1. IN PURSUIT OF A TRANS-CHELATING DIPHOSPHINE LIGAND
Jacqueline Dragon; Samuel Flanzman; Johann Frias; Michael Gao; JinOh Jeong; Angela Jin; Meeki Lad; Kevin Lin; Yuzki Oey; Jessica Teipel; Mathini Vaikunthan; Evan Zou
Advisor: Dr. Mary-Ann Pearsall
Assistant: Nicholas Chiappini
NJGSS 2014 Drew University – Team Project 3

2. Coordination Complexes
INTRODUCTION
Coordination Complexes B e- C M A
Some Ligand
Organometallic Complexes
Useful as catalysts
Possess other unique properties
Some Central Atom/Ion

3. Ligands and Chelation Halides Amines Diphosphine Carbonyls Phosphines
INTRODUCTION
Ligands and Chelation
Halides
Amines
Diphosphine
Carbonyls
Phosphines
Diphosphines chelate. That is, they can form coordinate covalent bonds in a complex at multiple sites.

4. The Experimental Goal INTRODUCTION Molybdenum Hexacarbonyl (Mo(CO)6)
Mo(CO)4[(Ph2P)(CH2)n(PPh2)]

5. Experimental Obstacles
INTRODUCTION
Experimental Obstacles
Molybdenum hexacarbonyl reacts with phosphenes in multiple ways
Monosubstitution
Disubstitution
Trisubstitution CO
PPh2
PPh2 CO CO Mo
PPh2 CO CO Mo
PPh2 CO Mo CO Mo CO Mo CO CO CO CO Mo Mo
PPh2 CO CO CO
PPh2 CO CO
PPh2 CO
PPh2 CO CO CO
Mo(CO)6
[(Ph2P) (CH2) n (PPh2) ]
CIS
TRANS

6. Activated Precursor Complexes
INTRODUCTION
Activated Precursor Complexes
PPh2 CO
How do we obtain a guaranteed trans product? CO CO
Use weak ligand (piperidine)
Resulting activated precursor complex always involves disubstitution and occurs in the cis form
Replace piperidine with diphosphine
Heat to convert to trans Mo CO
PPh2 CO CO
pip
pip
pip
pip
pip
pip

7. Varying Hydrocarbon Length
INTRODUCTION
LIGANDS
Varying Hydrocarbon Length
1,4
1,5
1,6
1,8
1,12
Longer hydrocarbon length = greater freedom of the diphosphine to chelate in a trans configuration

8. Hypotheses Expectations
INTRODUCTION
Expectations
Hypotheses
As the length of the hydrocarbon chain increases, the trans isomer will become more favorable.
Past a certain number of carbons, the hydrocarbon chain will be so long that it will form unintended alternate bonds.

9. Procedure and Rationale
EXPERIMENTAL
Procedure and Rationale
Day 2:
Mo(CO)4(pip)2 + [(Ph2P)(CH2)n(PPh2)] cis-Mo(CO)4 [(Ph2P)(CH2)n(PPh2)] + 2 pip
Heat
Day 3:
cis-Mo(CO)4 [(Ph2P)(CH2)n(PPh2)] trans-Mo(CO)4 [(Ph2P)(CH2)n(PPh2)]
Heat
Day 1:
Mo(CO)6 + 2 pip Mo(CO)4(pip)2 + 2 CO
Heat CO Mo
PPh2
PPh2 CO
pip CO
pip

10. Mo(CO)4 (pip)2 Mo(CO)6 Collecting Data – IR
EXPERIMENTAL
Collecting Data – IR
Infrared Spectroscopy is a method of identifying chemical compounds by their characteristic dipole shifts and consequent % transmittance readings.
This process was used at each experimental setup to confirm the presence of the desired compounds.
Mo(CO)4 (pip)2
Mo(CO)6
cis- Mo(CO)4 [(Ph2P) (CH2)n(PPh2)]
trans- Mo(CO)4 [(Ph2P) (CH2)n(PPh2)]
pip
Number of Distinct Dipole Shifts: 1
Expected Peaks:
Number of Distinct Dipole Shifts: 3
Expected Peaks:
Number of Distinct Dipole Shifts: 1
Expected Peaks:
Number of Distinct Dipole Shifts: 3
Expected Peaks:

11. Collecting Data – Nuclear Magnetic Resonance Spectroscopy
EXPERIMENTAL
Collecting Data – Nuclear Magnetic Resonance Spectroscopy
NMR is a method of spectroscopy that measures the alignment of phosphorus nuclei with a strong magnetic field, and in doing so, yields a graph that describes those atoms’ chemical environment.

12. Control Group, Ligand PPh3
RESULTS
Control Group, Ligand PPh3
cis-Mo(CO)4(PPh3)2
Mo(CO)4(PPh3)2 + Δ IR
NMR

13. 1,12 Group, Ligand (PPh2)2(CH2)12
RESULTS
1,12 Group, Ligand (PPh2)2(CH2)12
cis-Mo(CO)4[(Ph2P)(CH2)12(PPh2)]
Mo(CO)4[(Ph2P)(CH2)12(PPh2)] + Δ IR
NMR

14. 1,8 Group, Ligand (PPh2)2(CH2)8
RESULTS
1,8 Group, Ligand (PPh2)2(CH2)8
cis-Mo(CO)4[(Ph2P)(CH2)8(PPh2)]
Mo(CO)4[(Ph2P)(CH2)8(PPh2)] + Δ IR
NMR

15. 1,4 Group, Ligand (PPh2)2(CH2)4
RESULTS
1,4 Group, Ligand (PPh2)2(CH2)4
cis-Mo(CO)4[(Ph2P)(CH2)4(PPh2)]
Mo(CO)4 [(Ph2P)(CH2)4(PPh2)] + Δ IR
NMR

16. 1,5 Group, Ligand (PPh2)2(CH2)5
RESULTS
1,5 Group, Ligand (PPh2)2(CH2)5
cis-Mo(CO)4[(Ph2P)(CH2)5(PPh2)]
Mo(CO)4[(Ph2P)(CH2)5(PPh2)] + Δ IR
NMR

17. 1,6 Group, Ligand (PPh2)2(CH2)6
RESULTS
1,6 Group, Ligand (PPh2)2(CH2)6
cis-Mo(CO)4[(Ph2P)(CH2)6(PPh2)]
Mo(CO)4[(Ph2P)(CH2)6(PPh2)] + Δ IR
NMR

18. Discussion: Conclusions
ANALYSIS
Discussion: Conclusions
# of Carbons in Ligand
Ligand (Chemical)
Ligand (Structural)
cis-trans Conversion Notes 4
[(Ph2P)(CH2)4(PPh2)]
No Conversion 5 6
Some Conversion 8
Mostly Conversion 12
Increasing efficacy of cis-trans conversion

19. Ancillary Points
Hypothesis was based solely on ball-and-stick models and was proven correct
Knowledge of the spatial geometry can help predict the complex’s properties as well as those of similar complexes.
Applications of trans-chelating diphosphine ligands in catalysis can now be explored.

20. Dr. Mary-Ann Pearsall Nicholas Chiappini Acknowledgments
Independent College Fund of NJ/Johnson & Johnson
AT&T
Actavis Pharmaceuticals
Celgene
Novartis
Bayer Healthcare
Laura (NJGSS ’86) and John Overdeck
NJGSS Alumnae and Parents of Alumnae
Board of Overseers, New Jersey Governor’s Schools
State of New Jersey
Drew University